Convertible Notes (Interest Expense for the Series 2012 Notes) (Detail) (Series 2012 Notes [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Series 2012 Notes [Member]
Debt Instrument [Line Items]
Contractual coupon interest	$ 347	$ 1,290	$ 1,455	$ 3,864
Amortization of debt issuance costs	64	289	996	860
Amortization of debt discount	404	1,538	1,783	4,538
Total	$ 815	$ 3,117	$ 4,234	$ 9,262